The present invention relates to a heat exchanger intended for effecting an exchange of heat between two liquid media and comprising two heat-exchange chambers which are separated from one another in a liquid-tight fashion by means of a common liquid-impervious partition wall, and each of which is intended to be through-passed by a respective one of such two liquid media.
The heat exchanger according to this invention was developed primarily for use in automotive vehicles for cooling lubricating oil or hydraulic oil with the aid of the engine cooling water as the cooling medium.
The internal combustion engine of automotive vehicles is cooled primarily with water, or commonly with a mixture of water and glycol, which in turn is cooled in an air-water-cooler. In order not to subject the engine to excessive thermal stresses, the temperature of the water coolant is changed only to an insignificant extent during its passage through the air-water-cooler. Consequently, it is necessary to use a very large volumetric flow of cooling water in order to achieve the requisite engine cooling effect. In the case of modern engines, there is also a need to cool the engine oil, and in many cases also the oil in the vehicle transmission system. This can be achieved with the aid of air or by using the engine-cooling water as a coolant. Earlier it was quite usual to cool the oil by means of an air-cooler, but this method has become progressively less usual, since the coolers involved are bulky and a large number of coolers are required, which makes it difficult to utilize the cooling air-flow effectively. Consequently, it has become more usual to cool the oil with the engine cooling water as the coolant. In principle this can be effected in two different ways. The first of these methods involves the embodiment of a water-oil-cooler in the collecting box of the engine air-water-cooler. This arrangement is often used for cooling the oil in automatic gear boxes. In this case, the oil is led to the engine air-water-cooler through hoses. The second of the aforesaid methods involves passing the flow of engine cooling water, or a part thereof, to a water-oil-cooler which is placed close to the component whose oil is to be cooled. Thus, in this case it is water which is passed through hoses to the oil-water-cooler. One example of this particular arrangement is found in the engine oil coolers which are fitted between the engine block and the oil filter. Only a part of the total flow of engine cooling water is passed through these oil coolers. Since according to the first of the aforesaid methods, an oil cooler is placed in the collecting box of the engine air-water-cooler, it is difficult to avoid disturbing the function of the air-water-cooler, which is of prime importance for cooling the engine, or to avoid impairing the oil cooling conditions. Since according to the second of the aforesaid methods the oil-water-coolers are placed in the close vicinity of the components whose oil is to be cooled, a large amount of space is required to accommodate the oil-water-coolers of present day construction and a comprehensive and complicated network of pipes and hoses is required to conduct the cooling water to the coolers. Furthermore, conventional oil-water-coolers require a troublesome high pressure drop for the flow of cooling water, which is a drawback in engine-cooling-water systems.